Re: ShopTalk: Swing Weight fixture

[Ed Reeder]

Bob, First, here are some SW formulas/rules of thumb that may be of value to you: Grams needed to change 1 SW point Formula (varies by the length of the club): grams = 49.61 / (length – 14) For example, a 37" club will need a 2g (2.16g) weight difference to change the SW 1 point 2.16 = 49.61 / (37 -14) A 35.5" club 2.3g and a 45"  club will need 1.6g: Grams needed to change 1 SW Point Rule of Thumb 2g = 1 point SW change per Inch Rule of Thumb (the real SW formula is fairly complex, so this is generic - be conservative) 6 points per inch or .1667 inch per point /Ed How to achieve what you want: Assign Shafts to Heads Based upon raw-frequency, use the softest (and usually lightest) shafts with the longest clubs.  Since the shorter, heavier clubs have the most material trimmed you will end up with an overall lighter set of clubs.  If, for some reason, you want a heavier set of clubs, reverse the assignment process.  Also, if you have a head that needs a lot of extra weight, assign a heavy shaft to it; you’ll need to add less weight. Mark the club number on the shaft, near the shaft weight and length marks. Compute Swingweight Adjustments Now that you have: the heads assigned to the shafts; the weight adjustments needed to bring the head weights to spec; and weights of your other components, determine if any additional tip weighting is needed.  You can do this through the use of one of the swingweight calculators available on the Internet.  You should test your calculations as soon a possible with a dry assembled club.  In fact, if you are adding weight to the test clubhead, add less weight and test the swingweight.  It is easier to deal with a clubhead that is too light vs. one that is too heavy. If a head is too heavy, you will need to choose a lighter shaft, perhaps even a different model of shaft. Trim the Shafts These instructions assume you are not using butt-trim only shafts. Start with the longest club to make sure that the assigned shaft is stiff enough.  Also, if a mistake is made the shaft can usually be salvaged for use in a shorter club.  KEY CONCEPT: Leave an extra inch on the butt end of the club to give room to make weight adjustments to the head until the target SW is exactly where needed. You will have to add 6 SW points to the raw SW to compensate for the extra length, but that extra inch gives you room for additional tipping if needed to put you dead on your target frequency and SW as well as keeping kick points constant. It also eliminates blowing a shaft. Checking the Frequency 1.        Temporarily attach the head, and any tip weights, to the shaft using monofilament fishing line as a shim. Make sure the spine is properly aligned.  Mark the hosel depth before attaching the head to make sure it is fully seated. Be sure to attach the head not in the plane of eventual construction, but with the COG of the head in the plane of vibration (toe to target).  In this way, the head will not twist on the shaft and affect the FLO and/or frequency measurement when the shaft is plucked. 2.        Perform an initial tip trim, using the amount from the previous (longer club).  This works for “standard” frequency slopes. 3.        Mark the butt position at the proper length on the shaft, with masking tape.  That way the mark can be moved as the shaft is fine-tuned.  Remember to allow 3/16 inch for the grip cap. 4.        Check and adjust the FLO, especially if you are dealing with graphite shafts and have trimmed a significant amount..  Mark the FLO near the tip, so that it will be easier to align the clubhead during assembly. 5.        Measure the frequency. 6.        What is the frequency? a)       If it's just right, you have completed the tip trimming and the swingweight can be checked. b)       If it's too high, you have the wrong shaft. c)       If it's too low, trim some (Steel shafts generally get about 5-7 CPM stiffer for each 1/2" of tip trim, but test this with the shafts you use) The key is to tip trim in small increments.  All shafts react a little differently to trimming, so "sneak" up on the final frequency.  Graphite shafts can be especially individualistic in this regard.  The important thing to remember is that if you tip trim too much, you can use that shaft on a shorter club. Now: i.         Move the Mark, so the marked length is correct. ii.        Measure from butt and record tip trim for your records iii.      Re-measure the frequency, checking the FLO if need be. Checking the Frequency Example If your initial measurement on a 3-iron (with NO tip trim) is say 7 CPM lower than your desired frequency, you will probably have to tip trim around 1/2" to get the desired frequency.  For subsequent shorter clubs, start by tip trimming the amount used on the previous club, and then make final adjustments from there (i.e., for the 4-iron in this example, tip trim 1/2" first and then start fine tuning the final frequency). Check the Swingweight Prior to assembly you can double check your swingweight estimates.  It is best to do this without a grip (a 50g grip is almost exactly 10 points) and with the shaft one inch longer than your target (adds 6 points, for a total of 16 points). The extra length allows you adjust the club if needed.  (Don’t forget about the 3/16-inch grip cap allowance.  Use a 3/16-inch drill bit as a spacer when placing the shaft in the SW scale). Now you check the SW, with 3 possible outcomes: 1.        SW is just right - great!  Quit. 2.        SW is too low - add more tip weight (will reduce cpms), so you need more tip trim to get the frequency back up.  (Tip trim has more effect than butt trim, so the extra inch on the butt is priceless). 3.        SW is too high - use the shaft in next lower club.  Because, if you reduce tip weight (which will increase cpms) there is no way to decrease the cpms (except to increase the length of the club past your initial target) Bob Barrette wrote: Hi Colin: I didn't make myself clear enough. I do exactly what you are saying, I make sure that the heads are properly weighted, (7 gram progression).That will insure a very constant S/W through the set. Let us assume that they come out at C8 Say I have a customer that wants a D3 S/W throughout the set,now I have to add lead powder which will change the frequency! I am looking for a way that I can determine the final S/W, before I do the dry fitting, that way I can get the desired frequency and S/W. I hope this clears up what I am trying to accomplish!! Pinpoint customers who are looking for what you sell.